Vacuum pump



C. H. HAPGOOD VACUUM PUMP Filed May 3, 1924 s Sheets-Sheet 2 F/QE. I a

//W/vr0/? W/T/VESS."

Cyrus //0w'nr0 6a 0y0ac/ ATTORNEYS.

Aug. 2 1927.

C. H. HAPGOQD VACUUM PUMP Filed May 5, 1924 W/T/VESS: F/G

ATJURIIEKS Patented Aug. 2, '1927 UNITED STATES PATENT'OFFICE.

OYRUS HOWARD HAPGOOI), OF NUTLEY, JERSEY, ASSIGNOR TO THE DE LA'VAL SEPARATOB COMPANY, 01 NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

' vacuum rumr.

Application filed May 3,

In the patents to Leitch, No. 1,367,554,

' February 8, 1 921, and Hall, No. 1,374,650,

mercial use.

pump, the provision of the described air' channels in the housing requires the use of blind cores in the casting operation and involves also the cuttin of ports in the circular wall, or bore, 0 the housing. In my improved construction, the bore of the ho us-. ing is maintained imperforate and no bind cores are required in the casting operation. In the Leitch-Hall pump, the bore of the housing is of such shape that all diameters (or chords) measured through the center oi the shaft are equal. This involves giving an elliptical shape to the bore of the housing. Thisv operation requires highly skilled labor and care and if. not performed accurately, produces rough running of the rotor. In my improvement, the bore of the housing is made circular, with other modifications of construction to render a housing so shaped 0 erative. Not only is such a housing relatively easy and inexpensive to produce, but smoothness of operation is thereby secured with more certainty than in the older con struction. g The invention will be understood by reference to the drawings, which illustrate a preferred embodiment of the invention.

Fig. 1 is a cross-section through the housing, rotor and oil separator. v

Fig. 2 is a section, on a somewhat reduced scale, on the line 2-2 of Fig. 1; certainclements, such as the shaftdriving mechanism, lubricating oil channels, etc, being omitted. Fig. 3-is a section through the line 3 8 of Fig. 4 is a section through the linen-4 of Fi 1.

Fig. 5 is a section through the line 5-5 of Fig. 1. p a

The rotorais mounted on a shaft b carried by bearings in the heads c and 01. Between the lieads is a housing h. The bore of the housin is circular (a true cylinder). The shaft %is located on a diameter of the bore of the housing, but not at the center 19%. -Serial No. 710,780.

of the. bore. In the drawings, it is located directly above such center. Therefore, a horizontal chord through the center of the shaft is the shortest chord through the center of the shaft while a vertical chord through the center of the shaft (which coincides with the diameter of the housing) is the longest chord through the center of the shaft, other chords being of progressively variable mediate lengths.

tinuous contact with the circular bore'of thei housing. Preferably, although not necessarily, opposite vanes seat in their sockets at'the instant they occupy a position coincidentwith the shortest chord through the center of the shaft. In other ositions, one at least of the vanes moves radially outward so that its inner edge recedes from its seat, leaving a clearance, as shown at 3 Figs. 1

. and 2.

the bore of the housing at all times. Their provision, however, is distinctly advisable.

It is ObVl0llSl much easierto make the bore of the housing circular than to make it elliptical, especially where the ellipse must be formed so accurately-that all chords measured, through the centerj of the shaft are equal. Unless that is done quite accurately,

the pump will 'chatter more or less. In the present construction, not only is accuracy of contour much more easily secured, but.

(the left hand side, Figs. 1 and 3) is formed a long arcuate air inlet chamber i opening toward the housing and rotor. The .outer Wall of each chamber 2' is curved on an tic whose center is the center of the cylindrical housing. So, also, is the inner wall, throughout the greater part of its length. The outer wall of-each chamber 71 is'a substantial distance -beyond theJbore of the housing.

' In that end (the upper end)- of the chamber nearest the line of tangential contact between rotor and housing bore, the inner wall of the chamber coincides with theouter wall pf the rotor, whereby tendency toleakage of air is avoided. A cross-channel m is formed through the housing to connect opposite air chamb ers The housing is threaded at n to receive an air suction pipe (not shown)..

Within each head 0, d, at the upper righthand corner is formed an air outlet chamber or recess 0 opening inward. Theinner edge of each recess 0 overlaps the bore of the housing, aflording a slotted opening p -for passage of, air from thespace between the housing bore and rotor to such recess. The inner edge of each recess 0 throughout the greater part of its length is coincident with the outer wall of the rotor, so that the slotted opening 39 is tapered throughout the greater part of its length. In the housing are formed channels '1', 1', opening laterally into the respective recesses 0, 0, and communicating, through ports 8, s see Fig. 5), with the oil separator t (the specific construction of which need not be described, as it, forms no part of this invention). The oil separator is threaded in'its upper wall at u to receive an air exhaust pipe -(not shown). The construction -just described eliminates some of the worst of the cores required to make the form of Leitch-Hall construction specifically disclosed in the patents hereinbefore mentioned. Further, by providing for discharge or air through the side, instead of through the center of the housing, more space is allowed for the air to flow through'the separating chamber into the outlet 14. This construct or has been found by test to considerably relieve the back pressure on the discharge side of the pump, thus reducing the power conrotor and 'slidable radially therein, of a p I housing enclosing the rotor and vanes and having atrue circular bore whose center is ofiset relatively to the centenof the shaft, and slidable spacers between oppositely dis-. posed vanes limiting the approach of such vanes toward each other but permitting their relative-recession.

2. Ina vacuum pump of the sliding vane type, the combination with a driving shaft,

a rotor mounted thereon and oppositely disposed vanes extending through .slots in the rotor and slidable radially therein, of a housing enclosing the rotor and varies and having a true circular bore, the center of the shaft being positioned on a diameter of the housing bore at one side of the center thereof, and spacers slidable independently of the vanesand in the ends of which oppositely disposed vanes are adapted to seat, each spacer just filling'the space between such vanes when the same occupy a position on the shortest chord subtended by such vanes in their rotation. 0

3. In a vacuum pump of the sliding vane type, the combination with a driving shaft, a rotor mounted'thereon, a housing enclosing the rotor, and vanes extending through slots I in the rotor and slidable radially therein and engaging the bore of the housing, of heads closing the ends of the housing, each head provided with an air chamber the edge of which overlaps the bore of the housing and afiords a narrow opening for air communication between said chamber and the space between thebore of thehousing and the rotor,

the bore of the housing being imperforate.

4. In a vacuum pump of the sliding vane type, the combination with. a driving shaft,v

a rotor mounted thereon, a housing enclosing'the rotor and having an imperforate bore, and vanes e'xtendin through slots in the rotor and slidable ra ially therein and engaging the bore of the housing, of heads closing the ends of the housing, each head prcvided with an air chamber the edge of which overlaps the bore of the housingand afiords a narrow opening for air communication between said chamber and, the space between the bore of the housing and the rotor, the housing having a channel parallel to the axis of the shaft extending entirely through the housing and connecting the air chambers in opposite heads.

5. in a vacuum pump of the sliding vane type, the combination with a driving shaft,

ran

a rotor mounted thereon, a housing enclosing the rotor and having an imperforate bore,

and vanes extending through slots in the rotor and slidable radially therein and engaging the bore of the housing, of heads closing the ends of the housing, each head provided with an air chamber opening to- Ward the housing, the wall of the chamber nearest the center of the housing being, throughout the greater part of its length, curved on an are substantially concentric with the bore of the housing and aflording.

between it and said bore an elongated arcuate air -admission port. y 6. In a vacuum pump of the sliding vane type, the combination with a driving shaft, a rotor mounted thereon, a housing enclosin the rotor and whose bore is imperforate an is disposed eccentrically to, and tangentially engaged by, the rotor, and vanes extending through slots in the rotor and slidable radially therein and engaging the bore of the housing, of heads enclosing the ends of the.

housing, each head provided with an air chamber the edge of which overlaps'the bore of the housing and substantially coincidesalong part of its length with the outer cylindrical wall of the rotor.

l 7. In a vacuum pump of the sliding vane type, the combination with a driving shaft, a rotor mounted thereon, a housing enclosing the rotor and having an imperforate bore, and vanes extending through 'slots in the rotor and slidable radially therein anden- 7 'gaging the bore of the housing, of heads closing the ends of the housing, the wall of the chamber nearest the center of the housing being, throughout the greater part of its 8. In a vacuum pump of the sliding vane type, the combination with a driving shaft, a rotor mounted thereon, a housing enclosing therotor, and vanes extending through slots in the rotor and slidable radially therein and engaging-the bore of the housing, of

'heads closing the ends of the housing, each head provided with an air chamber the edge 'of which overlaps the bore of the housing and affords a narrow opening for air com- .munication between said chamber and the space between the bore of the housin and the rotor, said housing having, outsi e the wall forming its bore, a channel communie eating laterally with said chamber, and an oil separatin chamber outside said channel and communicating therewith.

In testimony of which invention,'I have hereunto set my hand at New York, on this 15th day of April, 1924.

CYRUS HOWARD HAPGOOD. 

